The invention relates generally to product coding and marking, and more particularly to thermal printer systems and methods for printing on elongated substrates, particularly non-flat at least temporarily deformable substrates including heat shrink tubing, among others.
The printing of variable information on elongated substrates including insulated electrical wire and heat shrink tubing in coding and marking operations has been performed in the past by both hot stamp imprinters and thermal printers.
Hot stamp imprinters have the advantage of leaving an impression on the substrate, wherein the ink is recessed below a surface thereof, where it is less susceptible to removal by abrasion. The impression on the substrate is also capable of conveying the imprinted information after the ink is removed, but the impression may have an adverse effect on the structural integrity of the substrate. Hot stamp imprinters have been particularly suitable for imprinting on non-flat, at least temporarily deformable substrates including less costly heat shrink tubing, particularly the smaller diameter tubing, which have diameters of 1/4 inch and less.
Thermal printers transfer ink from a print ribbon, or foil, onto the substrate by applying heat to the foil. In the past, information printed with thermal printers had a tendency to wear off over time, but advances in thermal ink compositions have substantially improved the durability thereof for all but the most demanding of applications, particularly some military applications, which have more rigorous specification requirements. Thermal printers are also programmable, which is a significant advantage over other printing systems. Thermal printers are, more particularly, capable of storing and recalling print data relatively easily and less costly than systems having type or dies, which are painstakingly laborious to set and assemble. Thus, there is an increasing tendency to utilize thermal printers in many coding and marking applications, including the marking and coding of elongated substrates.
In one known application, heat shrink tubing manufacturers, including the Raychem and Sumitomo companies, utilize thermal printers to print variable information on relatively expensive pre-flattened heat shrink tubing, particularly larger diameter tubing. According to one known proprietary system, pre-flattened heat shrink tubing is supplied to the thermal printer from a spool having barcode data thereon, which must be read by the thermal printer before printing. The proprietary thermal printer is programmed to permit printing on only tubing supplied from the spool with the barcode data, and moreover will not permit reuse of the spool by winding competitors', very likely less costly, tubing thereabout. Also, the thermal print head of the proprietary thermal printer is stationary relative to the direction the heat shrink tubing is fed, and thus prints as the substrate moves relative thereto. But this mode of operation limits the tubing feed rate since the tubing cannot be fed any faster than the rate at which the print head transfers ink from the foil onto the substrate, which limits productivity.
Thermal printers are generally incapable of printing on non-flattened substrates, like less costly heat shrink tubing, since ink will not transfer from the foil onto the curved surface portions thereof. Thus, in the past, only hot stamp imprinters were used for printing on non-flattened heat shrink tubing, as suggested above. In many thermal printers, including the proprietary thermal printing system discussed above, the substrate has a tendency to rub against the foil as the substrate is fed between the foil and a backup plate, which are spaced relatively closely. As a result, ink from the foil is inadvertently transferred onto the substrate, often leaving ink streaks thereon, which is not pleasing aesthetically and moreover may not comply with some industry and particularly military specifications.
Additionally, known hot stamp imprinters and thermal printers useable for coding and marking elongated substrates are capable of printing on only one substrate at a time, which further limits productivity.
The present invention is drawn toward advancements in the art of product coding and marking, and more particularly to thermal coding and marking systems and methods for printing on elongated substrates.
It is thus an object of the present invention to provide novel thermal coding and marking systems and methods therefor that overcome problems in the prior art, that are economical, and that are useable for printing on elongated substrates, especially generally non-flat at least temporarily deformable elongated substrates including heat shrink tubing, among others.
It is a further object of the invention to provide novel thermal coding and marking systems and methods therefor that increase productivity by feeding one or more elongated substrates in parallel past a thermal print head simultaneously and relatively quickly, that eliminate ink streaking or unintended printing on the substrate caused by rubbing thereof against the foil, and that compensate for misalignment of the print head with a backup plate.
It is a more particular object of the invention to provide novel thermal printer systems and methods for transferring ink from a foil onto elongated substrates, particularly non-flat at least temporarily deformable substrates including heat shrink tubing, by drawing a plurality of parallel elongated substrates past a thermal print head and adjacent the foil with a feed roller located downstream the thermal print head, at least temporarily deformably flattening portions of the plurality of elongated substrates by engaging the substrates with a pressure roller located upstream the thermal print head, and transferring ink onto the at least temporarily flattened portions thereof adjacent the thermal print head.
It is another more particular object of the invention to provide novel thermal printer systems and methods that increase tension on a portion of the plurality of elongated substrates adjacent the thermal print head by increasing drag on the pressure roller with a drag inducing member coupled thereto, and alternatively by feeding the substrate along a relatively circuitous path and over a fixed guide member.
It is another more particular object of the invention to provide novel thermal printer systems and methods that more readily at least temporarily deformably flatten elongated substrates by heating the elongated substrates upstream the thermal print head, and alternatively by feeding the elongated substrates between a resilient roller positioned adjacent the pressure roller.
It is still another more particular object of the invention to provide novel thermal printer systems and methods that stationarily position the plurality of parallel elongated substrates adjacent a print head, then movably sweep the print head substantially parallel to portions of the stationary substrates to transfer ink from the foil onto the substrates, and that subsequently draw the elongated substrates past the thermal print head at relatively high rates when not transferring ink onto the substrates.
It is yet another more particular object of the invention to provide novel thermal printer systems and methods that actuatably position a backup plate away from the foil when not transferring ink onto the elongated substrate to substantially eliminate unintended ink transfer thereon, and that compensate for misalignment of the thermal print head with a floatable resilient pad member disposed on the backup plate opposite the thermal print head.
These and other objects, aspects, features and advantages of the present invention will become more fully apparent upon careful consideration of the following Detailed Description of the Invention and the accompanying Drawings, which may be disproportionate for ease of understanding, wherein like structure and steps are referenced generally by corresponding numerals and indicators.